A liquid process is performed in a manufacture process of a semiconductor device by supplying liquid chemicals (e.g., a resist liquid, an acid or alkali cleaning liquid, a solvent, a precursor-containing liquid for forming an insulation film, etc.) from a nozzle to a substrate. Such a liquid chemical supply apparatus is configured to remove foreign substances by a filter unit disposed in a supply passage.
Bubbles may be created in the aforementioned process due to gas dissolved in a resist or a liquid chemical. A line width of a pattern becomes finer and finer. Thus, cautious measures should be taken for fine bubbles that are not problematic in the past.
A coating apparatus for coating the aforesaid liquid chemical performs a gas removal process of removing the gas in a filter unit in order to remove foreign substances contained in a process liquid. The gas removal process makes the process liquid permeate through the filter unit (hereinafter, referred to as “a filter wetting process”) when the filter unit is newly mounted or replaced. For example, as a method of performing the filter wetting process, filtering is performed under a positive pressure (pressure higher than an atmospheric pressure) using a pressure of a N2 gas or a pressure produced by a pump after setting the filter unit, and thereafter the number of defects on a substrate caused by the bubbles is monitored. Further, in the method of performing the filter wetting process, the gas in the filter unit is regarded as fully removed when the number of defects decreases to a predetermined level, and the filter wetting process is finished accordingly.
However, in this method, to reduce the cost for mass production, the process liquid amount consumed before the filter unit starts to operate should be reduced. Additionally, the operative time should be shortened.
By way of another example, the filter unit communicating with a process liquid ejecting nozzle may have a structural feature for reducing the number of bubbles in the process liquid passing through the filter unit. In this example, the filter unit may have repetitive prominences and depressions on a wall surface, but this may lead to complexity in manufacturing the filter unit.